The present invention relates generally to safety labels for fuel cans for heating chafing dishes, such as gel chafing fuel cans, e.g. Sterno(copyright) type cans. More specifically, the present invention relates to labels for Sterno(copyright) type chafing fuel cans that indicate the physical characteristics of the cans as they relate to temperature. The safety label provides information to the end user about the characteristics of the chafing fuel can through the use of a thermochromic ink that undergoes a sharp, reversible visible metachromism in response to a particular temperature change. The present invention also relates to a method of manufacturing labels for chafing fuel cans which utilize thermochromic inks to provide visual information about the physical characteristics of the as they relate to temperature.
Sterno(copyright) type and other similar chafing fuel cans are well known. These can heating elements typically are used for the heating of food inside of chafing dishes. Such chafing fuel cans are typically aluminum cans that are approximately two to three inches in height and have a retractable or removable lid. When the lid is removed, an ethanol fuel, a gel fuel, or other fuel disposed therein is exposed. This fuel, when ignited, provides an invisible flame (such as those associated with burning ethanol) that is capable of reaching temperatures of up to 500xc2x0 F. (260xc2x0xc2x0C.). Chafing fuel cans of this type are popular with consumers because of their ability to continuously heat food products in chafing dishes, coffee carafes, or other containers over extended periods of time.
One problem with such chafing fuel cans of this type is that they may be associated with burn injuries. Such injuries are sometimes caused because the invisible nature of the fuel. Users are often unable to determine whether or not the fuel is actually burning.
Moreover, burn injuries may also occur after the flame of the heating element is extinguished. For example, several minutes after the flame is extinguished, the surface temperature of such chafing fuel cans often remain elevated to the point where skin burns can still occur. Users who are unaware that the flame was recently extinguished, may handle the can prematurely and thereby burn themselves. Furthermore, burn injuries associated with chafing fuel cans may also occur because the user is unaware of the level of the fuel inside of the can. The fuel disposed in such chafing fuel cans burns extremely hot at and above the surface level of the fuel in the can. However, just below the surface level of the fuel, the temperature of the chafing fuel can is low enough for the user to safely handle the can""s exterior. Therefore, if the user is unaware of the level of the surface of the fuel within the chafing fuel can, accidental burn injuries may occur.
Another problem associated with the such chafing fuel cans is that there is currently no visual representation of the temperature at which the chafing can burns. The United States Food and Drug Administration requires that hot food be kept at or above 140xc2x0 F. in open air chafing dishes in order to be in the heated xe2x80x9csafe zone.xe2x80x9d When chafing dish food is kept above this temperature, a substantial amount of harmful bacteria is killed. Therefore, it would be advantageous to know whether or not the chafing fuel can is burning at or above 140xc2x0 F.
Due to the inherent dangers associated with any such lighted chafing fuel cans, it would be desirous to design a safety label for such cans that is capable of providing information to the user about the temperature characteristics of the chafing fuel can. Such a safety label would prevent many burn injuries associated with such cans. Currently, no safety labels for Sterno(copyright) and other type chafing fuel cans are available that are capable of providing this type of information to the user.
The invention satisfies the needs noted here by providing a safety label that is capable of visibly providing users of Sterno(copyright) and other type chafing fuel cans with a variety of information about the current physical characteristics of the cans as they relate to temperature. Thus, safety labels made in accordance with the invention will work to prevent burn injuries associated with chafing fuel cans by providing a visual indication of the actual elevated temperatures present with the cans. The visual indication on the present safety label is achieved through the use of a media such as an ink or paint with thermochromic materials dispersed therein.
Thermochromic materials that undergo sharp, reversible visual metachromism in response to temperature changes are known in the art. For example, U.S. Pat. No. 4,028,118 issued to Nakasuji et al. discloses such a material. Typically, these materials contain, as indispensable components, an electron-donating, chromatic organic compound, a compound having a phenolic hydroxyl group, and a compound selected from the group consisting of higher aliphatic monatomic alcohols and higher aliphatic monatomic acid alcohol esters.
In accordance with a fundamental aspect of this invention, there is provided a safety label for use with Sterno(copyright) and other type chafing fuel cans. The safety label contains at least one portion that includes media with thermochromic material dispersed therein. The media with thermochromic materials is capable of reversibly undergoing visible metachromism as it is exposed to increased temperatures, and returning to its original color as the temperature decreases, thereby permitting use as a safety indication of increased temperatures.